X-ray rates, Auger group rates, and X-shell fluorescence yields are presented for variously ionized states of neon. The nonrelativistic Hartree-pock-Slater atomic model, with the exchange approximation of Herman-Van Dyke4rtenburger, is used. The x-ray and Auger transition energies were obtained by the adiabatic method. The theoretical results presented here are applicable to the analysis of defect configurations which may be produced in a heavy-ion-neon collision. It is shown that the cotrtrrtonly used statistical scaling procedure to obtain the K-shell fluorescence yield for defect configuration leads to significant errors for neon.

We have measured cross sections for An = 1 dielectronic recombination (DR) on He-like argon and found good agreement with theoretical calculations based on the Hartree-Fock atomic model. Experimental absolute cross sections were obtained by using the electron-energy dependence of yields of Helike and Li-like argon ions from the Kansas State University electron-beam ion source to measure the ratio of the DR cross section on He-like argon to the electron-impact-ionization cross section of Li-like argon and normalizing to the latter. The K x-ray emission spectra due to hn =1,2 DR and n =1~2 electron-impact excitation of He-like argon were also observed with a Si(Li) detector placed at 0 relative to the electron-beam direction. By normalizing to the theoretical KLL integrated DR difFerential cross section, we obtained difFerential and partial difFerential DR cross sections and differential electronimpact excitation cross sections. We found good agreement with Hartree-Fock calculations for DR and with distorted-wave calculations for electron-impact excitation.

1919jority of the experiments done on laterally diffused light could be redone: Hanle effect of odd isotopes, double resonance in weak or strong magnetic field, level crossing in strong field, and study of the true resonance levels (some results were recently obtained'4 on the 5'P, level of Cd). We are continuing these experiments on the combined effect of multiple diffusion, collisions between mercury atoms, and collisions of excited atoms on the wall of the cell. On the other hand, the systematic study of the signals observed directly from the light emitted by a discharge lamp could give information on the radiative transfer in the lamp, resonant and nonresonant collisions and possibly information on the parameters associated with the discharge. It is certainly possible to appreciably improve the experimental setup to test in detail more elaborate theories which will eventually appear. ACKNOWLEDGMENTSOne of the authors (B. D. ) would like to express her gratitude to the University of New Hampshire

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We have used the electron-energy dependence of yields of heliumlike and lithiumlike argon ions from the Kansas State University electron-beam ion source (EBIS) to measure the ratio of the cross section for An -1 dielectronic recombination on heliumlike argon to that for electron ionization of lithiumlike argon. By normalizing to the latter cross section we obtain absolute dielectronic recombination cross sections and find good agreement with theoretical calculations for the lower-energy resonances.PACS numbers: 34.80.Dp, 32.80.Hd, 34.80.Kw, 52.20.Fs Dielectronic recombination (DR) of a free electron with an ionic target is the process whereby an electron of the core is collisionally driven to an excited orbit, with a change in principal quantum number hereafter designated by Aw, while the incident electron is itself captured into an excited orbit on the core, thus forming a doubly excited ion (atom). If the excited ion (atom) decays radiatively, the charge state of the system has decreased by one unit and recombination of ion and electron is accomplished. Since the doubly excited state has a discrete energy, the process is resonant in electron energy. It was shown by Burgess 1 in 1964 that DR generally proceeds at a higher rate than radiative recombination in hot plasmas, and it has come to be widely recognized 2 " 4 that this process plays a dominant role in determining the charge-state balance in the state of matter found m many fusion and astrophysical settings. In spite of the importance of this process, the first experimental measurements of DR cross sections for well-defined target ion and electron energy were not reported until 1983, 5 " 7 and all previous rates were based on theoretical calculations. While these and subsequent measurements 8,9 on AH-O transitions have led to valuable increased understanding of the DR process, the comparison between theory and experiment is complicated in these cases by the fact that the experimental cross sections measured receive large contributions from unresolved resonances which encompass a Rydberg series for the captured electron. The resonances lying near the series limit are substantially affected by the electric fields present in the experimental apparatus, and indeed the experiments have served to show in the laboratory that DR rates can be substantially enhanced by the presence of external electric fields. 8 Only very recently have experiments on A/2-0 transitions been able to obtain a resolution high enough that a clean comparison between theory and experiment for nearly isolated resonances may become possible. 10